Here's an application I designed as a Windows 7 tweak utility for The Windows Aero features associated with the taskbar specifically. There are various options/functions for the taskbar items themselves, as well as the taskbar preview thumbnails.

Everything except for the change for Taskbar item width requires a reboot, and if you changed the value from what it currently is, you'll be notified that a reboot is required, else you won't. However I didn't include an auto-reboot feature in my application as I think those things are annoying. All of the other changes get updated automatically when you press the "Update" button because explorer.exe gets restarted to initiate any new changes.

Most people don't know how to restart explorer.exe so if that wasn't available in my application, I think:

a) A lot of people would think that my application doesn't work
or Resorts to doing a full reboot, or log off, and log in process